Relationship between Exhaled Nitric Oxide and Childhood Asthma

Abstract

The purpose of the study was to determine if exhaled nitric oxide levels in children varied according to their asthmatic and atopic status. Exhaled nitric oxide was measured in a sample of 93 children attending the North West Lung Centre, Manchester, United Kingdom, for the clinical evaluation of a respiratory questionnaire being developed as a screening tool in general practice. The clinical assessment included full lung function, skin prick testing, and exercise challenge. Children were said to be asthmatic either by consensus decision of three independent consultant pediatricians, who reviewed all the clinical results except the nitric oxide measurements, or by positive exercise test. Atopic asthmatic children had higher geometric mean exhaled nitric oxide levels (consensus decision, 12.5 ppb [parts per billion] 95% CI, 8.3 to 18. 8; positive exercise test, 12.2 ppb 95% CI, 7.6 to 19.7) than did nonatopic asthmatic children (3.2 ppb 95% CI, 2.3 to 4.6; 3.2 ppb 95% CI, 2.0 to 5.0), atopic nonasthmatic children (3.8 ppb 95% CI, 2. 7 to 5.5; 5.7 ppb 95% CI, 4.1 to 8.0), or nonatopic nonasthmatic children (3.4 ppb 95% CI, 2.8 to 4.1; 3.5 ppb 95% CI, 3.0 to 4.1). Thus, exhaled nitric oxide was raised in atopic asthmatics but not in nonatopic asthmatics, and these nonatopic asthmatics had levels of exhaled nitric oxide similar to those of the nonasthmatics whether atopic or not.

Interrelationships among asthma, atopy, rhinitis and exhaled nitric oxide in a population‐based sample of children

“…In addition, our results suggest that the eNO level of atopic asthmatic children is greater than that of non-atopic asthmatic children. These findings are consistent with previous studies, in which eNO levels from two to four times higher than normal were found in atopic asthmatic children [7], teenagers [15] and adults [16]. Among non-asthmatic children, atopic subjects had higher eNO concentrations than non-atopic subjects, which contrasts with previous results showing no difference in eNO levels between atopic and nonatopic individuals either in children [7] or in adults [15,16].…”

Factors that influence exhaled nitric oxide in Italian schoolchildren

“…Thus, the association of asthma and atopy appears to be the most consistent predictor of increased eNO level. A similar result was obtained by Frank et al, 5 who found that the eNO geometric mean was significantly higher in children with atopic asthma than in nonatopic asthmatic children. These findings further support the hypothesis that in children atopy is a major determinant of increased eNO levels, mainly when associated with clinical manifestation of asthma.…”

“…[2][3][4] However, other studies did not find a relation between atopy and eNO levels in children. 1,5,15 In particular, Latzin et al 15 failed to demonstrate a relation between atopy and eNO levels in 4-to 18-year-old healthy children. A possible explanation for these conflicting results might be found in the dimension of the studied sample, 5 the different prevalence of atopic children in the study samples, and the different age distributions.…”

“…1,5,15 In particular, Latzin et al 15 failed to demonstrate a relation between atopy and eNO levels in 4-to 18-year-old healthy children. A possible explanation for these conflicting results might be found in the dimension of the studied sample, 5 the different prevalence of atopic children in the study samples, and the different age distributions. 15 In fact, in our study, the prevalence of atopy was 29% among asymptomatic children, and the age range was 10 to 16 years: The corresponding figures in the study by Latzin et al were 46% and 4 to 18 years, respectively.…”

“…[2][3][4] Consequently, it has been suggested that the relation between asthma and increased eNO levels may be mediated by atopy itself. 5 This suggestion emphasizes the key role of atopic inflammation in determining an increase in eNO production for allergic diseases such as asthma and rhinitis. 6,7 Nevertheless, some conflicting results exist about the meaning of eNO measures in epidemiologic studies.…”